Homokinetic joints are known from U.S. Pat. No. 3,218,827. Like the so-called cardan joints, they serve to transmit rotary motion from one rotating part to another rotating, driven part, when the rotational axes of these two rotating parts are not coaxial. Homokinetic joints consist essentially of an outer ring, flanged to the driven part, for example the wheel of an automobile, and an inner ring, fastened to the driving part, for example the drive shaft of an automobile. The inner ring has the approximate shape of a spherical disk, so that it can turn and swivel in the outer ring, whose interior is approximately cylindrical. Grooves, whose cross sections correspond approximately to 7/8 of a circle, are provided in the outer surface of the inner ring and the inner surface of the outer ring, whereby a ball is disposed in each groove of the inner ring and the corresponding groove of the outer ring. These balls are prevented by a cage from falling out of the grooves, which therefore serve as ball-bearing races.
Joints of this type have the considerable advantage that, unlike cardan joints, the driven part does not receive any of the rotary oscillating movement superimposed on the rotational movement, whereby a rotational oscillating movement of this type, which appears superimposed in the case of cardan joints, depends upon the angle between the axis of the driving part and the axis of the driven part.
The grooves in the inner and outer rings, which serve as ball-bearing races, do not run parallel to the rotational axes of these rings, but are inclined at an angle to these axes. Moreover, these grooves can always be inclined in the same direction, in other words parallel to one another or differently from one another, whereby the angle of inclination relative to the axis is always the same, regardless of the amount.
In a vertical broaching machine, known from U.S. Pat. No. 3,799,030, for broaching such rings of homokinetic joints, a workpiece grip is provided, by means of which the workpieces are removed from the workpiece holder after broaching and delivered to an indexing device in which they are turned through a set angle, for example 120.degree. when there are three groove pairs, and then returned to the workpiece holder. A prismatic wedge is provided on the broaching machine for tangential, axial, and radial location of the workpiece on the workpiece holder, said wedge being supported on the one hand by wedge-shaped surfaces in a corresponding recess in a holding pin on the workpiece holder, and being provided on the other hand with a convex surface on its exterior, said surface engaging a previously broached ball-bearing race, thereby guiding and locating the workpiece axially, tangentially, and radially. When broaching a first pair of ball-bearing races, the prismatic wedge engages the corresponding recess in the holding pin only with that part of its cross section which is located at its free end. In the vicinity of this free end, the prismatic wedge is provided with a surface that rests against the inside wall of the workpiece. Broaching machines with this workpiece holder have proven to be extremely satisfactory in principle. In the case of tolerances amounting to several microns in the bore of the workpiece, however, the result is that corresponding defects appear in the position of the grooves to be broached relative to the axis of symmetry of the workpiece. Furthermore, it is costly from the structural standpoint, time-consuming during the manufacturing process, and a source of additional inaccuracies in manufacture if the workpieces have to be removed from the workpiece holder between the individual broaching steps.